Byrne announced the decision in a news release, stating his involvement in "certain government matters," which he confirmed in another statement earlier this month, would negatively affect the online retailer's business.

"Though patriotic Americans are writing me in support, my presence may affect and complicate all manner of business relationships," he said. "Thus, while I believe that what I did was necessary for the good of the country, for the good of the firm, I am in the sad position of having to sever ties with Overstock."

Byrne released a statement on Aug. 12, confirming a report by journalist Sara Carter that said he delivered documents to the U.S. Department of Justice regarding his involvement assisting federal authorities that he referred to as "the Men in Black" in their "Clinton investigation" and "Russia investigation."

He also confirmed that he was romantically involved with Russian gun activist Maria Butina for three years. Butina was sentenced to 18 months in prison in April after pleading guilty to one count of conspiracy to act as a foreign agent for infiltrating various conservative U.S. political groups.

Overstock appointed Jonathan Johnson III as its interim CEO and Kamelia Aryfar as a member of its board of directors following Byrne's resignation.

"Jonathan's diverse and extensive experience here has prepared him well to successfully oversee both our retail and blockchain businesses," Byrne said. "Kamelia is a brilliant machine learning scientist and ecommerce veteran who has already made great contributions to our science, engineering and analytics by advancing data-driven technology. Her addition to the board will continue to propel Overstock forward in its visionary direction."